This invention relates to a cart type conveying apparatus used in various fields of industry to convey various articles along a predetermined conveying route.
The cart type conveying apparatus comprises a guide rail having a substantially U-shaped section and including an upper horizontal extension and a lower horizontal extension, a conveyor cart including trolleys guided by the guide rail, supporting wheels supported to be rotatable on horizontal axes at lower positions of the trolleys, retaining wheels supported to be rotatable on horizontal axes at upper positions of the trolleys, lower centering rollers supported to be rotatable on vertical axes at the lower positions of the trolleys, and upper centering rollers supported to be rotatable on vertical axes at the upper positions of the trolleys. The conveyor cart generally includes a drive trolley and a follower trolley, and a carrier bed is supported by or suspended from these trolleys. Each of the trolleys is provided with the wheels and the rollers noted above.
As shown in FIGS. 7 and 8 of the accompanying drawings a known conveying apparatus of this type comprises a guide rail 1 including an upper extension 51 and a lower extension 52 defining guide ridges 53 and 54, respectively. Lower centering rollers 55 are opposed to each other across lateral sides of the ridge 54, and upper centering rollers 56 are opposed to each other across lateral sides of the ridge 53. Supporting wheels 57 are mounted on an upper face of the ridge 54 of the lower extension 52. Retainer wheels 58 are placed in contact with a lower face of the ridge 53 of the upper extension 51.
In the drawings, number 59 denotes a drive trolley having an electric motor 60, number 61 denotes a follower trolley, number 62 denotes a carrier bed, numbers 63 and 64 denote bed supporting arms, number 65 denotes an electric conductor and signal transmitter unit, number 66 denotes a collector unit, number 67 denotes a pair of upper and lower rail covers, and number 68 denotes guide rail support stands.
The carrier bed 62 and the supporting arms 63 and 64 are pivotally interconnected to be oscillatable on vertical axes 69 and horizontal axes 70 to permit the cart to travel smoothly through horizontal and vertical curves. Therefore, each of the trolleys 59 and 60 has one supporting wheel 57 and one pair of retaining wheels 58. Further, each trolley has the lower centering rollers 55 at one position and the upper centering rollers 56 at two positions longitudinally of the cart. In other words, where the carrier bed 62 and the supporting arms 63 and 64 are rigidly interconnected, only one retaining wheel 58 is required and the upper centering rollers 56 may be provided at one logitudinal position. But, to permit the drive trolley 59 and the follower trolley 61 to control their own postures, it is necessary to provide a pair of forward and rearward retaining wheels 58 and the upper centering rollers 56 at two longitudinal positions as described above.
The drive trolley 59 and the follower trolley 61 are capable of controlling their own postures by providing a pair of forward and rearward supporting wheels 57, one retaining wheel 58, the lower centering rollers 55 at two longitudinal positions, and the upper centering rollers 56 at one longitudinal position. But then the supporting wheels 57 should desirably have a large diameter to bear a great load, and generally only one supporting wheel is provided. It will be understood that either the upper or lower centering rollers 55 or 56 may be provided at two longitudinal positions.
According to the cart type conveying apparatus as noted above, since the lower centering rollers 55 and the upper centering rollers 56, respectively, are disposed opposite each other across the ridges 53 and 54, it is necessary to secure spaces for permitting passage of the centering rollers 55 and 56 laterally of the ridge 54 on which the supporting wheels 57 run and the ridge 53 on which retaining wheels 58 run. Although the spaces for the centering rollers 55 and 56 disposed outwardly of the guide rail 1 may be secured with little problem, the spaces for the centering rollers 55 and 56 disposed inwardly of the guide rail 1 can be secured only by elongating the upper extension 51 and the lower extension 52. This results in disadvantages of requiring a large amount of material for forming the guide rail 1 thereby increasing the manufacturing cost and of heavy guide rail 1 which renders installation work difficult.
Furthermore, since the lower centering rollers 55 and the upper centering rollers 56 perform their centering function by being disposed at both lateral sides of the ridges 53 and 54, the centering rollers 55 and 56 inevitably are provided in a large number. Accordingly, the apparatus includes a large number of components which not only makes assembly work troublesome but results in increased manufacturing cost and increased weights of the trolleys 59 and 61.
Where each of the trolleys 59 and 61 is adapted to control its own posture by means of the centering rollers 53 and 54 provided at both lateral sides of the ridges 53 and 54, each trolley must have as many as six centering rollers 55 and 56.